airMessages interactive density exploration

Steven StrachanHamilton Institute

Roderick Murray-SmithUniversity of Glasgow

andHamilton Institute

http://www.dcs.gla.ac.uk/~rod

• We introduce here a system that offers a general mechanism for providing highly interactive context-aware applications.

• In our example application we use the system to guide users to messages left in the local augmented virtual/physical environment.

• This system may be used in a more general way to allow users to probe and explore local contextual areas of interest.

Mobile Sensing: MESH• Modality Enhancing Sensor-pack for Handhelds• Designed for the IPAQ range of pocket PCs• Physical design same as the PCMCIA expansion

jacket• Triple-Axis acceleration sensing

– MEMS Accelerometers– Orientation sense and gesture capture

• High Fidelity Vibrotactile Display– Sample based, Non-Volatile sample

storage,Audio bus-driven option– Actuator – VBW32 rewound

• Triple-axis magnetometer– Orthogonal Magneto-Resistive elements

• Capacitive sensing• GPS

Next sensor pack.. SHAKE

• Our next generation pack…• Bluetooth, wireless and compact• Accelerometers, gyros, magnetometers and haptic

feedback.• Use for head, device or bimanual gestures.

GPS Navigation Problem

• GPS is useful but inaccurate• Inaccuracy varies in a complex way

– Reflections, shadowing, poor coverage– Could use hybrid positioning

• General problem – accurate representation of belief and trustworthiness

Uncertain Display

• Poor displays lead to poor control• Norman's example of The Royal Majesty

“precise” position

Uncertainty in GPS Navigation

• Represent and display the true uncertainty of the navigation system – make it “honest”

• realistic display should regularise control behaviour

• Incorporate models

• environment models

• user models

• Monte Carlo sampling is a convenient statistical technique for dealing with uncertainty

GPS Model

• Uncertainty in location– Affected by nearby occlusions– Also reported from GPS device

• Can model areas of coverage with shadow maps [Steed 2004]

– Trace visibility of satellites given a known map of buildings

Shadow Map Example

– Raytraced fromsatellite positions

– Darker regionsindicate areasof lower coverage

User Behaviour

• Model user as dynamic system– Heads in current direction (e.g. from

magnetometer heading)– Flows around obstacles

•Gradient following model is simplistic but sufficient.

Complete Model

• Represent current user position as samples from a Gaussian distribution– Mean at current GPS location– Variance determined by shadow mapping

• Propagate those samples through a simple gradient following model– Display resulting particle distribution at some time

horizon

• the major benefit of this work is the introduction of a new kind of rich, embodied and location-aware spatial interaction with the environment.

A rich and embodied interaction

• enables a user to interact and traverse densities which they place over the real world.

• This system utilises both audio and vibrotactile feedback.

• The audio feedback consists impact sounds generated using granular synthesis– …these impacts are also mapped into vibrotactile

feedback.

Feedback…

System Testing

• Initial testing was conducted to demonstrate that users could find and leave messages in their virtual environment.– 6 participants

• Participants followed a set scenario around an area of the campus

• All participants successfully completed the task required of them.

• Not all participants really used the interface to its full potential.

• Conclusion

•Experimental participants performed well and had a natural intuition for the task, which meant that learning was quick.

•It is hoped that this system will aid the creation of a new kind of location-aware computing, one which allows a rich and embodied spatial interaction with the local environment.

•We have demonstrated that the probabilistic, negotiated interaction techniques can be applied effectively to the mobile GPS navigation problem.